No, you're thinking of the old Sovtek 7591-XYZ, which was just a rewired Sovtek 5881, and did need a circuit change to replace a regular 7591A (needed about twice the bias voltage for the same plate current).

The new Electro-Harmonix 7591A plugs in and biases up just like a 7591A is supposed to, the only thing it's got in common with a Sovtek 5881 is the bulb.